1. Field of the Inventions
The present inventions relate generally to fuel supply devices for an engines, and more particularly, to fuel supply systems for outboard motors that supply fuel to a vapor separator tank positioned adjacent to an engine from a main fuel tank disposed in a hull by a low pressure fuel pump.
2. Description of the Related Art
Some of the known outboard motor designs include a vapor separator tank disposed within the upper cowling of the outboard motor. For example, Japanese Patent Document JP-A-Hei09-144617, in at least FIG. 2 thereof, discloses such an outboard motor. In this outboard motor, both a vapor separator tank and a low pressure fuel pump are positioned on a side of and adjacent to the engine, within the cowling.
The vapor separator tank accumulates fuel to be supplied to the engine, and also has a high pressure fuel pump therein. A high pressure fuel supply conduit is connected to the vapor separator tank to supply the fuel discharged from the high pressure pump to fuel injectors. Also, a high pressure fuel return conduit is connected to the fuel injectors to return the surplus of the fuel to the vapor separator tank.
The low pressure fuel pump is used to supply the fuel to the vapor separator tank from the main fuel tank in the hull of the associated boat. The low pressure fuel pump is positioned on a side of and adjacent to the engine, and is mounted on the engine via a bracket. An upstream side low pressure fuel supply conduit is coupled with a fuel suction port of the low pressure fuel pump and extends to the main fuel tank in the cowling. A downstream side low pressure fuel supply conduit is coupled with a discharge port of the low pressure fuel pump and extends to the vapor separator tank.
A manually operated primer pump and a fuel filter are situated midway of the upstream side fuel supply conduit. The primer pump is used to supply the fuel to the low pressure fuel pump from the main fuel tank.
A switching valve is placed at a fuel inlet port of the vapor separator tank, to which the downstream side low pressure fuel supply conduit is connected, to be opened or closed by a float floating in this tank. The switching valve is closed when a surface of the liquid fuel in the vapor separator tank reaches the preset maximum level. The valve is opened when the surface of the fuel falls to a level lower than the maximum level. As such, the low pressure fuel pump supplies the fuel from the main fuel tank in the hull of the boat to the vapor separator tank in the outboard motor, and the high pressure fuel pump supplies the fuel in the vapor separator tank to the fuel injectors.